Letter writing is an excellent way of slowing down this lunatic helterskelter universe long enough to gather one’s thoughts - Nick Bantock (British artist and author)

Griffin and Sabine were more than penpals

Nick Bantock wrote a series of books in the form of removable richly decorated letters and postcards, the first published and a best seller in 1991. The story is between two characters, Griffin and Sabine, the books beautifully illustrated with riveting artwork, some have described as disturbing.

A rather strange description for some rather strange books. Completely epistolary in its telling, the story of Griffin 
and Sabine (and, later, Matthew and Isabelle) chronicled through a series of postcards and letters, some of which come stuffed into envelopes glued to the page, which the reader must remove, unfold and read, as if snooping through the neighbor's mail. It was a novel idea at the time that having recently reread the original trilogy for the first time in over a decade, now feels almost quaint; what was once innovative now seems like an artifact from the distant past, adding a fascinating layer to the reading experience. - The Globe and Mail

In the first book, "Griffin and Sabine: An Extraordinary Correspondence" (1991), Griffin Moss, an unhappy artist living in London receives a strange postcard from Sabine Stohem, a woman he doesn't know who is also an artist and designs postage stamps for a fictional set of islands in the South Pacific called the Sicmon Islands and the two began to correspond. Through these letters they fall in love in spite never having met. Sabine admits to watching his art over the years and reveals she shares his vision: "When you draw and paint I see what you're doing while you do it". Over time Griffin begins to fear Sabine only exists in his mind and turns down her offer to come to her at her home.
The second book, "Sabine's Notebook: In Which the Extraordinary Correspondence of
Griffin and Sabine Continues" (1992). Sabine will not be dismissed and comes to Griffin's home in London while he travels through Europe, Africa, and Asia in search of himself. 
The third (and last one I read), "The Golden Mean: In Which the Extraordinary Correspondence of Griffin and Sabine Concludes" (1993) the reader begins to side with Griffin, that Sabine is a figment of his imagination, each seems unable to exist in the presence of the other. Yet they are bound to each other and struggle against the forces that keep them apart. Sabine's visions of Griffin's work begins to suffer as well as the emergence of a sinister stranger that follows her everywhere she goes.
I've never forgotten these books, the beautiful way they were produced and at the time of this post I find myself curious to revisit the ones I've read and move into the ones never discovered: "The Gryphon: In Which the Extraordinary Correspondence of Griffin and Sabine is Rediscovered" (2001), "Alexandria: In Which the Extraordinary Correspondence of Griffin and Sabine is Illuminated" (2003), and "The Pharos Gate: Griffin and Sabine's Lost Correspondence" (2016). There is a kickstarter for an interactive version of the books and I'm looking forward to viewing its metamorphosis into a new format.